1. Field of the Invention
The present invention relates to a container for use in a rechargeable battery and an electric double layer capacitor, as well as a battery and an electric double layer capacitor using the container and, more specifically, the present invention relates to a thin battery used for small-sized electronic equipments such as mobile phones and an electric double layer capacitor used for back-up power sources for semiconductor memories and secondary power supply systems for small-sized electronic equipments, as well as a container used for them.
2. Description of the Related Art
In recent years, along with remarkable development of portable equipments typically represented by mobile phones, portable computers, compact video cameras, etc., reduction in the size and the weight has been demanded further. Then, along with increasing demand for batteries as the power supply for such portable equipments, studies for reducing the size and the weight have been conducted vigorously by increasing the energy density of the battery. Particularly, since lithium battery uses lithium of small atomic weight and having high ionization energy, the lithium battery can be a battery capable of obtaining high energy density, being reduced in the size and the weight and, further, capable of recharging, and the lithium battery has been studied vigorously and become used at present for extensive application use including power supplies for portable equipments.
The battery is generally classified into a cylindrical type and a square type and has a structure in which a positive electrode material and a negative electrode material are contained via a separator in a container such as a cell casing made of metal and an electrolytic solution is injected and sealed therein.
Further, in the electric double layer capacitor, positive and negative charges are opposed at an extremely short distance along an interface where two different phases (for example, a solid electrode and an electrolytic solution) are in contact with each other. The electric double layer capacitor is an electric element capable of charging or discharging electric energy by utilizing electrostatic adsorption/desorption of ions at the ion adsorption layer in the electrolytic solution formed on the surface of a carbon material such as graphite, boronated graphite, activated carbon or coke used for positive electrode and negative electrode materials, that is, the electric double layer formed at the surface of the carbon material such as graphite used for the positive and negative electrode materials.
Then, thin rechargeable battery or electric double layer capacitor in which a battery element or an electric double layer capacitor element comprising the positive electrode, the negative electrode and the separator, and an electrolytic solution are contained in a ceramic base as shown in FIG. 10 has been proposed (refer, for example, to Japanese Unexamined Patent Publication JP-A 2001-216952).
A rechargeable battery or electric double layer capacitor according to the related art comprises a container, a positive electrode material A-1, a negative electrode material A-2, a separator A-3 and an electrolytic solution A-4. The container basically includes a ceramic base 11 such as formed of sintered alumina having a metallized layer 11d also serving as a positive electrode plate at a bottom and a lid body 14 made or metal such as an iron(Fe)-nickel(Ni)-cobalt(Co) alloy also serving as a negative electrode plate. The rechargeable battery or the electric double layer capacitor according to the related art is of a hermetically sealed structure having the container in which the separator A-3 containing the electrolytic solution A-4 sandwiched between the positive electrode material A-1 and the negative electrode material A-2 is disposed between the metallized layer 11d and the lid body 14. Charge and discharge at the metallized layer 11d and the lid body 14 is conducted by way of a first conductive layer C electrically connected with the lid body 14 and a second conductive layers D electrically connected with the metallized layer 11d formed at the lower surface of the substrate 11. Further, a frame member 13 can be provided between the ceramic base 11 and the lid body 14 (refer, for example, to Japanese Unexamined Patent Publication JP-A 2004-227959 (pages 4 to 6, FIG. 1)).
In the rechargeable battery or electric double layer capacitor E using the ceramic base 11 shown in FIG. 10, since the ceramic is excellent in the chemical resistance, the ceramic base 11 is less corroded by the electrolytic solution A-4 containing an organic solvent, acid, etc. and the electrolytic solution A-4 is not degraded by the intrusion of an impurity dissolved from the ceramic base 11 into the electrolytic solution A-4, and the performance of the rechargeable battery or electric double layer capacitor E can be maintained favorably.
However, since a metal layer 11c or the frame member 13 for bonding the lid body 14 to the ceramic base 11 is made of the metal, use of the high performance electrolytic solution A-4 cause a problem that these metal is dissolved into the electrolytic solution A-4 to degrade the electrolytic solution A-4.